Recent idr updates make idr_find() trigger WARN_ON_ONCE() before
returning NULL when a negative ID is specified. Apparently,
posix-timer::__lock_timer() was depending on idr_find() returning NULL
on negative ID, thus triggering the new WARN_ON_ONCE(). Make
__lock_timer() first check whether @timer_id is negative and return
NULL without invoking idr_find() if so.
Note that the previous code was theoretically broken. idr_find()
masked off the sign bit before performing lookup and if the matching
IDs were in use, it would have returned pointer for the incorrect
entry.
Signed-off-by: Tejun Heo <t...@kernel.org>
Reported-by: Sasha Levin <sasha.le...@oracle.com>
Cc: Thomas Gleixner <t...@linutronix.de>
---
Sasha, can you please test whether this makes the warning go away?
Thanks.
kernel/posix-timers.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index b51bb08..92465f9 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -637,6 +637,9 @@ static struct k_itimer *__lock_timer(timer_t timer_id,
unsigned long *flags)
{
struct k_itimer *timr;
+ if ((int)timer_id < 0)
+ return NULL;
+
rcu_read_lock();
timr = idr_find(&posix_timers_id, (int)timer_id);
if (timr) {
--
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